Seminar given to the Redwood Center for Theoretical Neuroscience at UC-Berkeley on March 6, 2008. Speaker is Peter Robinson of the Brain Dynamics Center, Westmead Millenium Institute, Westmead Hospital and Faculty of Medicine, University of Sydney.
Neural activity in the brain has been observed for over a century and is widely used to probe brain function and disorders, through the electroencephalogram (EEG), functional MRI, and other measures. However, the connections between stimuli, physiology, processing, and measurements have been chiefly qualitative until recently, and most applications of EEG and fMRI have been based on phenomenological correlations. A quantitative model of brain activity is described that includes key features of physiology and anatomy from microscopic synapses to the whole brain. Its parameters measure quantities such as synaptic strengths, signal delays, cellular time constants, and neural ranges, and are all constrained by independent physiological measurements. The model successfully predicts a wide range of EEG and other phenomena, including time series, spectra, evoked responses to stimuli, seizure dynamics, visual gamma (40 Hz) correlations during perception, measurement effects, arousal dynamics, and pharmacological influences. Fitting to experimental data enables physiological parameters to be inferred in normal and abnormal conditions.